1. Field of the Invention
The present invention relates to a component-embedded board incorporating an electric component and a method of manufacturing the same.
2. Description of the Related Art
Miniaturization and high functionality of electric equipment has been achieved as well as miniaturization of electronic components incorporated in equipment. Even for a printed wiring board for mounting electric components, higher density, multilayer, multi-layering, and enhancement of high-speed transmission characteristics are required. As a technology to meet these requirements, there is a packaging technology called EWLP (Embedded Wafer Level Package). EWLP is a technology for mounting semiconductor components (electric component) such as a WLCSP (Wafer Level Chip Size Package) to a printed wiring board. According to EWLP, it is possible to improve the packaging density, reduce the wiring length between the semiconductor elements, and enhance the high-speed transmission characteristics.
A component-embedded board is known in which an electric component is embedded in a double-sided wiring board and a single-sided wiring board is laminated on both sides thereof (see Japanese Unexamined Patent Application, First Publication No. 2008-270362).
FIG. 18 is an example of a component-embedded board. The component-embedded board 100 includes a double-sided wiring board A103 in which a conductive layer 4 is formed on both faces of an insulation resin layer 3, and single-sided wiring boards A101, A102, A104, and A105 in which the conductive layer 4 are formed on the outer side of the insulation resin layer 3. One and the other faces of the double-sided wiring board A103 are provided with the single-sided wiring boards A101, A102, A104, and A105. An electric component 2 is embedded in an opening portion 103a of the double-sided wiring board A103.
The wiring boards A101-A105 are adhered together with an adhesion layer 5 and electrically connected to each other through an interlayer conductive portion 1.
FIG. 19 and FIG. 20 are a process drawing showing an example of a method of manufacturing a component-embedded board 100. The manufacturing method includes: disposing single-sided wiring boards A102 and A104 which are provided with the adhesion layer 5 on one face and the other face of the double-sided wiring board A103, respectively, such that the adhesion layer 5 opposes the double-sided wiring board A103; and collectively laminating them.
In the component-embedded board 100, both faces of the electric component 2 need to be covered by adhesive material (adhesion layer 5) in view of improving the durability. For this reason, the single-sided wiring boards A102 and A104 are disposed such that their adhesion layers 5 face the inner-layer side (toward wiring board A103).
When another single-sided wiring board is added at the outer-layer side of the single-sided wiring boards A102 and A104, the additional single-sided wiring board is also disposed such that its adhesion layer faces the inner-layer side. In this structure, when an electric component needs to be embedded in the additional single-sided wiring board as well, another adhesion layer needs to be provided on a face of the electric component so as to face the inner-layer side.
However, when such an additional adhesion layer is formed, the total thickness of the adhesion layer will increase, which causes a problem in that the whole thickness of the component-embedded board will increase.
The present invention was made in view of the above-described circumstances and the object thereof is providing a component-embedded board and a method of manufacturing the same which enable a reduction of the whole thickness of the component-embedded board incorporating an electric component to be achieved.